This invention relates to the collection of solar radiation and, more particularly, to solar panels of the nontracking type.
Most prior solar panels are of the moveable tracking type, or the fixed-position non-tracking type. Tracking type solar panels maintain fairly constant collection efficiencies by actually tracking the sun and focusing collected solar radiation upon a suitable energy conversion device or media. Panels of this type, however, require relatively complex and, hence, costly positioning apparatus for maintaining the panel in proper longitudinal and elevational alignment with the longitudinal axis of solar travel over the collector during each solar day, and throughout the solar year.
Non-tracking solar panels do not require such positioning apparatus, typically can circulate larger amounts of heat exchange fluid, and generally are less expensive than tracking type panels. Non-tracking flat panels which include a single planar absorptive surface are ineffective on a seasonal basis because they provide peak collection efficiency at only one solar position. The non-tracking panels or solar heat collectors disclosed in U.S. Pat. Nos. 3,991,740, 3,986,491, 3,915,148, and 2,625,930, however, take into account variations in the angle of incident solar radiation during a solar day, or a solar year, as the case may be, and therefore maintain higher seasonal collection efficiencies more akin to those obtained by tracking type solar panels.
Until this invention, however, non-tracking solar panels or solar collectors have been unacceptable in many practical applications incident to the provision of simplified light weight, low cost solar heating systems for use with homes and other buildings. Typical panels or collectors of this type, especially those panels or collectors designed to take into account variations in the angle of incident solar radiation as exemplified by the panels or collectors disclosed in the aforementioned United States patents, utilize complicated focusing or reflective elements for directing incident solar radiation toward an appropriate heat collector, storage or utilization device, or media. Although the reflective or focusing elements used do not move, they must necessarily be of relatively complex construction in order to accomodate the range of incident radiation angles encountered throughout each solar year, or each solar day, as the case may be. Consequently, they tend to be costly and/or bulky, and require substantial ancillary reinforcement or support in order to make them acceptable for installation and use with commercial home solar heating systems.
The simple roof covering disclosed in the U.S. Pat. No. 3,001,331, also takes into account the variation in the angles of incident solar radiation; but does not provide solar heat collection, solar heat impinging on the roof structure being reflected during the summer and absorbed during the winter.